Container Network Interface (CNI)

CNI is a set of standards that define how program should be developed to solve networking challenges in a container run time environment. This program is referred to as CNI plugin.

A CNI plugin is responsible for inserting a network interface into the container network namespace (e.g., one end of a virtual ethernet (veth) pair) and making any necessary changes on the host (e.g., attaching the other end of the veth into a bridge)

Any container runtime should be able to work with any CNI plugin.

CNI comes with a set of supported plugins such as

BRIDGE

MACVLAN

VLAN

IPVLAN

There are other plugins also available from third party organizations such as

Weave

Calico

VMware NSX

Flannel